Propofol EC50 for Inducing Loss of Consciousness in General Combined Epidural Anesthesia

The beneficial of perioperative usage of thoracic epidural anesthesia and analgesia in various thoracic and upper abdominal surgery are well studied. However, intraoperative data are lacking whether combined thoracic epidural and general anesthesia have effect on the median (50%) effective effect-concentration (EC50) of propofol for inducing loss of consciousness (LOC). We performed this study among patients undergoing open gastrectomy in gastric cancer patients. Sixty patients undergoing open gastrectomy were randomly assigned to two groups with thoracic combined general anesthesia (TEA+GA) or general anesthesia (GA) alone. Target-controlled infusion (TCI) of propofol was used for anesthesia induction. The initial propofol concentration of target effect-site (Ceprop) was 3.5 ug/ml and was increased stepwise by 0.5ug/ml at each 4 min intervals by an un-down sequential method to reach LOC. The predicted Ceprop at the time of LOC, intravenous anesthetics, vasopressor requirement, emergency time from anesthesia and postoperative numeric rating scale (NRS) were recorded and analyzed between two groups.